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Medicine > SUGER > Flashcards

SUGER Flashcards

1
Q

Rare disease in Europe defined as…

A

Affecting 1/2000 or less

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2
Q

Kidney roles

A

Maintain balance of salt, water, pH
Excrete waste products
Endocrine function
Control BP
RBC production
Maintenance of bones
Removal of drugs from body

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3
Q

Components of nephron in cortex

A

Bowman’s Capsule
Proximal tubule
Distal Tubule

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4
Q

Components of nephron in medulla

A

Loop of Henle
Collecting Duct

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5
Q

Renal cardiac output

A

~5 L/min

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6
Q

Renal blood flow

A

~1 L/min

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7
Q

Renal blood pathway

A

Abdominal aorta
Renal artery
Interlobar artery
Arcuate artery
Interlobular artery
Afferent arteriole
(nephron) Glomerular capillary
Efferent arteriole
Peritubular capillaries
Vasa recta
Interlobular veins
Arcuate veins
Interlobar veins
Renal veins
IVC

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8
Q

Renal urine flow

A

1 ml/min

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9
Q

The Tubuloglomerular Feedback Loop

A

Increased arterial BP
= Increased blood flow and BP in glomerulus
=Increased GFR
= Increased delivery of NaCl to macula densa (this triggers afferent arteriolar constriction)
= Decreased blood flow and BP in glomerulus

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10
Q

Myogenic mechanism for kidney autoregulation

A

Increased BP
= Stretch in vessel walls
= Opens stretch-activated cation channels
= Membrane depolarisation
= Opens voltage-dependent Ca channels
= Increased intracellular Ca
= Smooth muscle contraction
= Increased vascular resistance
= Minimised change in GFR

(decreased BP does the opposite)

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11
Q

Autoregulation of the kidney comes with 2 mechanisms:

A

-Tubuloglomerular feedback
-Myogenic mechanism

Which maintain GFR and control water/waste excretion

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12
Q

3 components of kidney filtration barrier

A

Fenestrated capillary endothelium

Glomerular basement membrane

Podocytes (foot processes)

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13
Q

5 factors affecting glomerular filtration

A

Pressure
Molecule size
Charge of molecule
Rate of blood flow
Binding to plasma proteins

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14
Q

Small molecules and ions up to …. can pass freely through filtration barrier

A

10kDa (glucose, uric acid, K)

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15
Q

Why can’t negatively charged ions cross filtration barrier?

A

Fixed negative charge of glomerular BM repels negatively charged anions

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16
Q

GFR is…

A

Glomerular filtration rate (filtration volume per unit time)

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17
Q

Embryology of pancreas

A

At junction of foregut and midgut, 2 pancreatic buds (dorsal and ventral) are generated which fuse to form pancreas

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18
Q

When does exocrine function of the pancreas begin?

A

After birth

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19
Q

When does endocrine function of the pancreas begin?

A

Weeks 10-15

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20
Q

Size of pancreas

A

12-15cm

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21
Q

Anatomical position of pancreas

A

Retroperitoneal, posterior to greater curvature of stomach

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22
Q

Ejaculate is a mixture of…

A

Spermatozoa and Seminal Plasma

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23
Q

Anterior covering of testes

A

Saclike extension of peritoneum (tunica vaginalis)

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24
Q

Tunica albuginea

A

White fibrous capsule
Septa dividing the testis into compartments containing seminiferous tubules

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25
Q

Where in the testes are spermatozoa produced?

A

Seminiferous tubules (where meiosis occurs)

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26
Q

What are the Leydig cells?

A

Cluster of cells between the seminiferous tubules and source of testosterone

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27
Q

Blood-testis barrier

A

Formed by tight junctions between sertoli cells (separates sperm from immune system)

And basement membrane beneath sertoli cells

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28
Q

Sertoli cell role

A

Promote sperm development (through testosterone production)

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29
Q

What do the seminiferous tubules drain into?

A

Network called rete testis

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30
Q

Pendulous pouch holding the testes divided into 2 compartments by…

A

A median septum

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31
Q

Testicular thermoregulation is necessary because…

A

Sperm aren’t produced at core body temperature (about 34 degrees)

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32
Q

2 types of daughter cells produced by spermatogonia

A

Type A Spermatogonia - remain outside blood-testis barrier and produce more daughter cells until death

Type B - Differentiate into primary spermatocytes

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33
Q

In spermatogenesis, meiosis I produces…

A

2 secondary spermatocytes from 1 primary spermatocyte

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34
Q

In spermatogenesis meiosis II produces…

A

4 spermatids from 2 secondary spermatocytes

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35
Q

Spermiogenesis is…

A

Transformation of spermatids to spermatozoa (sprouts tail and discards cytoplasm to become lighter)

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36
Q

3 regions of tail of a spermatozoon

A

Midpiece - contains mitochondria around axoneme of flagellum

Principal piece - axoneme surrounded by fibres

End piece - axoneme only

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37
Q

Length of cycle of seminiferous epithelium (sperm from spermatogonia)

A

16 days

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38
Q

Seminal fluid produced together by…

A

Bulbourethral, prostate and seminal glands

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39
Q

Fluid expelled during orgasm

A

2-5mL fluid
60% seminal vesicle fluid
30% prostatic
10% sperm
Trace of bulbourethral fluid

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40
Q

Normal sperm count

A

50-120 million/mL

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41
Q

Menstruation cycle summary

A

Days 1-7: Menstruation (3-7 days)

Days 8-11: Lining of womb thickens in prep for egg

Day 14: Ovulation

Days 18-25: If fertilisation hasn’t taken place, corpus luteum fades away

Days 26-28: Uterine lining detaches leading to menstruation

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42
Q

2 things responsible for sperm movement in female reproductive tract

A

Sperm motility
Female reproductive tract movement

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43
Q

2 features of PCTs

A

Simple cuboidal brush border (cells as deep as hairs are long)
High mitochondrial density

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44
Q

PCT function

A

Bulk reabsorption of Na, Cl, H2O, glucose, amino acids, bicarbonate, lactate, phosphate

Secreting organic ions

Na+/K+ pump for Na reabsorption

Other molecules taken up by secondary active transport, diffusion or osmosis

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45
Q

Water reabsorption in PCTs

A

By AQP1 channels
Water can also pass through the leaky tight junctions

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46
Q

Glucose reabsorption in PCTs

A

Early parts - SGLT2 - 1 Na+ and 1 glucose

Later parts - SGLT1 - 2 Na+ and 1 glucose

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47
Q

Sodium reabsorption in PCTs

A

Na+ actively transported out of PCTs via K+/Na+ (3Na+ out and 2K+ in)

This decreases Na conc in cell increasing gradient for Na+ to go lumen -> PCT cell

Na+ transported into cell either in exchange for H+ or co-transported

From cell, it’s pumped into the interstitium by Na/K ATPase or co-transported with bicarbonate

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48
Q

Amino acid reabsorption in PCTs

A

Co-transported with Na+

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49
Q

Chloride reabsorption in PCTs

A

Exchanged for formate in the NKCC2 channel
Formate then becomes formic acid (can diffuse across membrane and be reused)

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50
Q

Protein endocytosis and degradation in PCTs

A

Protein shouldn’t be in tubules but a mechanism is present for removing them

Microvilli have sensors which specifically bind any protein

Endocytosis occurs in endosomes and protein degradation by lysosomes producing amino acids

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51
Q

Bicarbonate reabsorption in PCTs

A

In lumen, H+ combines with HCO3- to form carbonic acid (requires carbonic anhydrase)
H2CO3 then -> H2O + CO2
CO2 diffuses through cell wall
H2O reabsorbed by osmosis

In cell, H2O + CO2 -> H2CO3 -> H+ + HCO3-
H+ recycled with transporting Na+
HCO3- co-transported with Na+ into interstitium (1Na+ with 3HCO3-)

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52
Q

Urachus

A

Remnant of channel between bladder and umbilicus

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53
Q

Renal plasma flow per minute

A

700ml/min

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54
Q

GFR

A

120ml/min

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55
Q

Renal blood flow

A

1250ml/min

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56
Q

How much bicarbonate water secretion does the pancreas produce per day?

A

1 litre per day

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57
Q

Role of pancreatic bicarbonate secretion

A

Protection of duodenal mucosa by neutralising stomach acid
Buffers duodenal content to optimise pH for enzyme digestion

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58
Q

Pancreatic proteases

A

(Protein digestion is initiated by pepsin in stomach and majority occurs in small intestine)

Trypsinogen and chymotrypsinogen which are transported in secretory vesicles containing a trypsin inhibitor (additional safeguard to prevent cell digestion)

Trypsinogen activated by enterokinase (secreted by small intestine epithelial cells)
Trypsin then activates chymotrypsinogen and additional trypsinogen
At this point the trypsin inhibitor is ineffective

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59
Q

Fat digestion due to 2 secretions

A

Pancreatic and hepatic secretions

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60
Q

Pancreatic amylase

A

Major source of amylase (salivary amylase has a small role)
Hydrolyses starch to more soluble sugars

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61
Q

Gastric secretion split into 2 stages

A

Cephalic stage - vagal innervation stimulates production of salivary amylase in mouth and gastrin in stomach (anticipation of a meal)

Intestinal stage - secretion of:
Cholecystokinin, secretin and gastrin

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62
Q

Cholecystokinin stimulus, produced in and action

A

Stimulus - HCl, protein, fats entering duodenum

Produced in - I cells of duodenum/jejunum

Action - Triggers pancreatic enzyme and HCO3- secretion, gallbladder contraction (releasing bile), inhibition of gastric secretion, delayed gastric emptying

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63
Q

Secretin stimulus, produced in and action

A

Stimulus - Low duodenal pH

Produced in - Upper small intestine

Action - Pancreatic water and bicarb secretion (flushing out into duodenum carrying enzymes)

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64
Q

Gastrin stimulus, produced in and action

A

Stimulus - Gastric distension/irritation

Produced in - G cells in stomach

Action - HCl secretion (parietal cells) enzyme release (acinar cells)

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65
Q

As proteins and fats are digested and absorbed, pH rises. What effect does this have on CCK and secretin secretion?

A

Stimuli for CCK and secretin disappear and pancreatic secretion reduces

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66
Q

Pancreatic endocrine function

A

Insulin and glucagon secretion

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67
Q

Difference in reabsorption between PCTs and DCTs

A

PCT - Bulk absorption, leaky

DCT - Fine tuning of filtrate, impermeable

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68
Q

Counter-Current Multiplication Mechanism in Loop of Henle

A

Generation of hyperosmotic interstitium to aid CT in water reabsorption by features of the thick ascending limb and thin descending limb

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69
Q

Role of thick ascending limb in developing a hyperosmotic interstitium

A

Driven by Na+/K+ ATPase pump on basolateral membranes of cells which keep intracellular Na low allowing ease of Na re-uptake

NKCC2 uses the gradient and pumps Na+ out lumen

K+ recycled on apical membrane back into lumen through ROMK channels

Cl- leaves cells through CLCK A channels (CLCK B in inner medulla) on basolateral membrane

Process promotes +ve charged lumen repelling Ca,Mg,Na ions which leave lumen

Creates a hyperosmotic interstitium

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70
Q

2 hormones secreted by posterior pituitary gland

A

Vasopressin (ADH) - controls water secretion into urine (primarily from supraoptic nuclei)

Oxytocin - expression of milk from glands of breasts to nipples, promote onset of labour (myometrium contraction) (primarily paraventricular nuclei). Stimulated by milk suckling.

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71
Q

Origin of posterior pituitary

A

Neuro tissue - large number of Glial-type cells

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72
Q

Max urine osmolality

A

1200mOsm/l
(In collecting tubules)

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73
Q

What inhibits ADH release?

A

Caffeine, alcohol

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74
Q

What stimulates ADH release?

A

Increased osmolality
Decreased blood volume
Nausea, vomiting, stress, exercise

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75
Q

Osmolality

A

Concentration of particles per kilo of fluid

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76
Q

Vasopressin mechanism of action of collecting tubules

A

Vasopressin binds to receptor on collecting duct cell membrane

Receptor activate cAMP second messenger system

Cells into aquaporins into apical membrane

Water reabsorbed by osmosis into blood

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77
Q

Restoration of osmolality by 2 ways

A

Increased plasma osmolality =

-Increased thirst -> Increased fluid intake -> restored osmolality

  • Increased ADH neurone firing -> release of ADH -> ADH at V2R -> Water reabsorption -> restored osmolality
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78
Q

Normal Osmolality

A

285-295 mOsmol/kg

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79
Q

3 skin layers

A

Epidermis
Dermis
Subcutis

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80
Q

Skin as a waterproof barrier

A

Tights junctions between cells in straum granulosum, epidermal lipids and keratin in straum corneum form both an inside-out and outside-in barrier to water

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81
Q

Epidermis functions

A

Waterproofing
Physical barrier
Immune function
Vit D synthesis (endocrine)
UV protection
Thermoregulation

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82
Q

Dermis functions

A

Thermoregulation
Vit D synthesis (endocrine)
Sensory organ

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83
Q

Subcutis

A

Thermoregulation
Energy reserve
Vit D storage
Endocrine organ
Shock absorber

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84
Q

Why does skin wrinkle when wet?

A

Skin on fingers and toes wrinkles if immersed for approx 5 mins
Mediated by sympathetic NS
Due to vasoconstriction in dermis
Improves grip

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85
Q

Skin as a physical barrier

A

Stratified epithelium helps resist abrasive forces
Fat in subcutis acts as shock absorber
Structure of skin helps resist trauma

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86
Q

Vitamin D synthesis in skin

A

7-dehydrocholesterol in plasma membranes of epidermal keratinocytes and dermal fibroblasts converted to previtamin D3 (cholecalciferol) by UV

15-25 min whole body exposure produces up to 10,000 IU Vit D

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87
Q

How is Vitamin D stored?

A

It’s lipid soluble so can be stored in subcutis adipocytes

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88
Q

Dietary Vitamin D intake

A

Vitamin D2 - Fish, meat Vitamin D3 - supplements

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89
Q

Skin as a site of hormone action

A

Androgens act on follicles and sebaceous glands

Thyroid hormones act of keratinocytes, follicles, dermal fibroblasts, sebaceous glands, endocrine glands

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90
Q

Skin as a site of hormone synthesis

A

Vit D unique site for cholecalciferol synthesis

17beta-hydroxysteroid dehydrogenase in sebocytes and 5alpha-reductase in dermal adipocytes convert dehydroepiandrosterone (DHEA) and androstenedione to 5alpha-dihydrotestosterone

Insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) synthesised by dermal fibroblasts)

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91
Q

What rays is skin a barrier to?

A

UV-A and UV-B which damage skin (burns, photo-aging, DNA damage)

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92
Q

Skin colour depends on…

A

Melanin
Carotenoids
Oxy/deoxyhaemoglobin

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93
Q

Melanin synthesis and transport

A

Synthesised in melanosomes within melanocytes from tyrosine
Transported by dendrites to adjacent keratinocytes

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94
Q

Colour of melanin

A

Pheomelanin - red/yellow

Eumelanin - brown/black

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95
Q

The more eumelanin your skin contains…

A

The darker your skin (we all have the same number of melanocytes but different amount of melanin)

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96
Q

Which type of melanin do we have most of in the skin?

A

Eumelanin

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97
Q

Deleterious effects of melanin

A

Prone to photodegradation (may generate ROS)

Pheomelanin increases release of histamine

Lots of melanin = less able to utilize UV light to make Vit D

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98
Q

3 stages of response to sunlight

A

Immediate pigment darkening
Persistent pigment darkening (tanning)
Delayed tanning

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99
Q

Immediate pigment darkening in response to sunlight

A

Photooxidation of existing melanin
Redistribution of melanosomes
Occurs within minutes and lasts hours/days

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100
Q

Persistent pigment darkening

A

Oxidation of melanin
Occurs within hours lasting 3-5 days

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101
Q

Delayed tanning

A

Increased melanin synthesis
Occurs 2-3 days after UV exposure (maximal at 10-28 days)

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102
Q

Skin as a barrier to infection

A

Properties that render skin a barrier to water also help prevent infection
Range of peptides synthesised by granular layer keratinocytes have antimicrobial properties

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103
Q

Skin as a sensory organ

A

Merkle cells - basal epididymis (light touch)
Encapsulated mechanoreceptors in dermis
Myelinated and unmyelinated sensory nerve endings in dermis (pain, itch temperature)

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104
Q

What connects seminiferous tubule to epididymis?

A

Seminiferous tubules -> Straight tubules -> rete testis -> Epididymis

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105
Q

How many primordial follicles in ovary at birth?

A

400,000 (approx 400 will mature and ovulate)

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106
Q

Insulating role of skin

A

Insulation by subcutaneous fat

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107
Q

Cutaneous blood flow in heat loss

A

Deep vascular plexus (lower reticular dermis)
Superficial vascular plexus (upper reticular dermis)

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108
Q

Autonomic regulation of blood flow in dermal vascular plexuses

A

Sympathetic alpha-noradrenergic: vasoconstriction

Sympathetic cholinergic: vasodilation

(both in hairy skin, hairless skin only has adrenergic innervation)

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109
Q

Eccrine sweat glands

A

1.6-4 million in skin
1-3 L sweat per hour
Water availability major limiting factor

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110
Q

Piloerection (goosebumps)

A

Arrector pili muscles innervated by sympathetic alpha1-adrenergic fibres
Contraction raises cutaneous hairs

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111
Q

Epidermis immunity role

A

Keratinocytes secrete cytokines and chemokines to maintain leucocyte populations in skin

Langerhans cells are antigen-presenting cells and secrete cytokines

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112
Q

Immune cells in dermis

A

Regulatory T cells
Natural killer cells
Dendritic cells
Macrophages
Mast cells

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113
Q

98-99% of pancreatic cells are…

A

Glandular epithelial cells forming clusters called acini

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114
Q

What is pancreas exocrine function?
Which cells carry it out?

A

Secrete pancreatic juice (enzymes an fluid released into gut)

Performed by acinar cells

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115
Q

What is pancreas endocrine function?
Which cells carry it out?

A

Several peptide hormones (insulin, glucagon) released into portal vein

Performed by islet cells (Islets of Langerhans)

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116
Q

Delta cells of pancreas secrete…

A

Somatostatin (acts as an inhibitor across a lot of systems)

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117
Q

Alpha cells of pancreas secrete…

A

Glucagon

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118
Q

Beta cells of pancreas secrete…

A

Insulin

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119
Q

Insulin secretion from pancreas mechanism

A

GLUT2 glucose transporter (low affinity) on membrane of beta-cell brings glucose into cell where glucokinase phosphorylates it to glucose-6-phosphate which increasing rate of ADP->ATP

ATP closes K+ channel on membrane resulting in depolarisation of membrane

This opens a voltage-gate Ca channel causes influx of Ca2+ into cell

Triggering exocytosis of proinsulin (which is contained within vesicles)

Proinsulin then splits into C peptide and insulin

120
Q

Biphasic insulin release

A

1st phase response - rapid release of stored product

2nd phase - slower release of newly synthesised hormone

121
Q

Insulin action in muscle and fat cells

A

Insulin binds to receptor on membrane

This signals GLUT4 vesicles to travel to membrane and get incorporated into membrane

High Affinity GLUT4 receptor drags glucose into cell

(Insulin effectively provides more ‘doors’ for glucose to leave cell)

122
Q

Glucose Homeostasis: short and long term response to high blood glucose

A

Short Term - Make glycogen
Long Term - Make triglyceride (lipogenesis)

123
Q

Glucose Homeostasis: short and long term response to low blood glucose

A

Short Term - Split glycogen
Long Term - Gluconeogenesis from AAs, fats, etc.

124
Q

Incretins (e.g - GLP-1)

A

Gut hormones that stimulate beta-cells to release insulin whilst dampening down effect of alpha-cells (which release glucagon)

They also delay gastric emptying (so feel full for longer)

125
Q

What prevents hypoglycaemia caused by incretins?

A

DPP-IV cleaves GLP-1 (incretin) rendering it inactive so can’t stimulate beta-cells or slow down rate of gastric emptying

DPP-IV levels rise as GLP-1 levels rise

126
Q

Factors affecting blood pH

A

Respiratory component: CO2 conc

Metabolic component:
Intrinsic acid (metabolised)
Extrinsic acid (diet)
Buffering capacity (bicarbonate

127
Q

DCT role

A

Fine tuning of Na reabsorption, K and acid-base balance

Impermeable to passive movement of water and Na

Uses NCCT (Na/Cl) co-transporter to reabsorb last bit of Na

128
Q

2 cell types in collecting ducts

A

Principal cells - Na, water reabsorption and K excretion

Intercalated cell (alpha or beta) - secrete H+ or HCO3- (pH balance)

129
Q

Aldosterone effect on principal cells

A

Aldosterone binds to receptors on principal cells in CTs which increases number of open ENaC channels

ENaC channels are a Na transporter

130
Q

GFR regulated by 2 things

A

Sympathetic NS
Hormones

131
Q

Sympathetic NS effect on GFR

A

Afferent (and efferent but less so) arterioles receive sympathetic innervation

Strong symp stimulus = constricted afferent arteriole = reduced renal blood flow = reduced GFR

132
Q

How to increase GFR through changing width of afferent and efferent arteriole?

A

To increase GFR either dilate afferent arteriole or constrict efferent arteriole (opposite to decrease GFR)

133
Q

Stages of menstrual cycle

A

Follicular Stage - Days 1-13/14

Ovulation - Days 13/14

Luteal phase - Days 14-28

134
Q

What difference does presence of Y chromosome make?

A

SRY gene triggers testicular development
Testis produce MIF preventing Mullerian duct development

135
Q

Production of primary oocytes in utero

A

Rapid meiotic division from 12 weeks results in 5-10 million primary oocytes at 20 weeks
Rapid cell death leaves 1 million primary oocytes at birth

136
Q

Primordial follicle is…

A

1 oocyte surrounded by granulosa cells
Secretes oestrogen, progesterone, inhibin

137
Q

Primordial follicle becomes…

A

Primary follicle - oocyte grows and becomes separated from granulosa cells by zona pellucida (contains glycoproteins, binds sperm)

138
Q

Primary follicle becomes…

A

Preantral follicle - granulosa cells differentiate into Theca cells (both function together for oestrogen synthesis)

139
Q

Preantral follicle becomes…

A

Early antral follicle - Primary oocyte full size
Antrum forms full of fluid secreted from granulosa cells

140
Q

Early antral follicle becomes…

A

The mature (Graafian) follicle after day 7 of each cycle
At beginning of each cycle, 10-15 pre/early antral follicles develop and grow
After 7 days, 1 follicle is dominant
Non-dominant follicles undergo atresia
Dominant follicle increases in size as does it’s antrum
Oocyte emerges from meiotic arrest due to LH surge
Completes its 1st division becoming a secondary oocyte
This increase in size ballooning out of ovary (ovulation)
Enzymatic digestion ruptures follicle and oocyte carried away by antral fluid

141
Q

Where are cells in ovaries arrested before sexual maturity?

A

Primordial follicles containing primary oocytes (FSH, LH secretion at sexual maturity)

142
Q

What stimulate FSH and LH release from anterior pituitary on days 6-7 of menstrual cycle?

A

GnRH from hypothalamus

143
Q

Mucus secretion in menstrual cycle

A

High oestrogen = abundant clear/watery mucus (good for sperm movement)

Progesterone and oestrogen = thick and sticky (stop entry of bacteria)

144
Q

3 stages of uterine changes

A

Menstrual phase (days 1-5): withdrawal of progesterone = endometrial degeneration (trigger of menstrual flow)

Proliferative phase (days 5-14): oestrogen from granulosa and theca cells causes endometrium to thicken
Also stimulates myometrium contraction and progesterone receptor generation in endometrium

Secretory phase (days 15-28): Progesterone binds with its receptors on endometrium
Endometrium secretes glycogen from glandular epithelium (sperm and oocyte nutrition)
Progesterone overrides oestrogen to prevent myometirum contraction and prostaglandin secretion

145
Q

Prostaglandins role in menstrual cycle

A

Dilate cervix aiding myometrium contraction

146
Q

Oestrogen secretion in menstrual cycle

A

In follicular phase secreted by granulosa cells
In luteal phase secreted by corpus luteum

147
Q

Progesterone secretion in menstrual cycle

A

In follicular phase made by granulosa and theca cells

In luteal phase made by corpus luteum (in much larger amount)

148
Q

Inhibin role in menstrual cycle

A

Decreases FSH
Peaks for ovulation
Decreases as corpus luteum degenerates

149
Q

LH secretion throughout menstrual cycle

A

Constant for most of follicular phase

LH surge - peaks about 18 hours before ovulation (generated by high oestrogen levels from maturing follicle)
Acts on hypothalamus and anterior pituitary to increase sensitivity to GnRH (+ve feedback)
LH surge allows oocyte to complete meiosis I

LH decrease - After ovulation, progesterone production = decrease in LH levels

150
Q

LH action on Theca cells

A

Stimulates them to produce androgens which are converted to granulosa cells to produce oestrogen and antral fluid

151
Q

Changes in FSH throughout menstrual cycle

A

Increases in early part of follicular phase
Slow decrease in levels throughout menstrual cycle
As 1 follicle beo mes dominant, more oestrogen = decreased FSH
Increase in FSH at day 10/11 triggering LH receptors to develop on Theca cells (presence of inhibin then actively inhibits FSH release)

152
Q

Luteal Phase

A

Completion of meiosis I results in ovulation
Corpus luteum formed
Low LH maintains corpus luteum
Results in secretion of progesterone and oestrogen
-ve feedback - decreased GnRH and therefore decreased FSH and LH
After 14 days of no fertilisation, corpus luteum dies removing -ve feedback so LH and FSH rise (cycle repeats)

153
Q

Meiotic arrests in females

A

Arrested in prophase I maturation during menstrual cycle
Arrested at metaphase II until ovulation
Meiosis completed after fertilisation

154
Q

Spermatogenesis location, meiotic divisions and germ line epithelium involvement

A

Occurs entirely in testes
Equal division of cells
Germ line epithelium is involved in gamete production

155
Q

Oogenesis location, meiotic divisions and germ line epithelium involvement

A

Occurs mostly in ovaries
Unequal division of cytoplasm
Germ line epithelium not involved in gamete production

156
Q

Number and size of gametes produced in spermatogenesis

A

4 sperm that are smaller than spermatocytes

157
Q

Number and size of gametes produced in oogenesis

A

1 ova (plus 2-3 polar bodies) larger than an oocyte

158
Q

Spermatogenesis timing

A

Uninterrupted process
Begins at puberty
Continuous release
Lifelong (reduces with age)

159
Q

Oogenesis timing

A

Arrested stages
Begins in foetus (pre-natal)
Monthly from puberty
Terminates with menopause

160
Q

Constituents of semen

A

10% bulbourethral
30% prostate
60% seminal vesicles

161
Q

How much semen secreted during orgasm?

A

2-5mL

162
Q

Normal sperm count

A

50-120 million/mL

163
Q

Sperm route

A

Seminiferous tubules
Rete testis
Efferent ducts
Epididymis
Vas deferens
Ejaculatory duct
Urethra
Penile urethra

164
Q

Functions of semen

A

Buffers against acidic environment
Chemicals like fructose to increase motility
Prostaglandins present to stimulate female peristaltic contractions

165
Q

Blood-Testis Barrier

A

Seminiferous tubules bound by a BM
Sertoli cells extend from BM into lumen
They’re joined to adjacent cells by tight junctions and form an unbroken ring inside seminiferous tubule
So sertoli cells form the B-T B preventing movement of chemicals

166
Q

Length of spermatogenesis process

A

64 days

167
Q

Spermatogonia divide mitotically at puberty into 2 types…

A

Type A - remain outside B-T B and produce more daughter cells
Type B - in basal compartment (primary spermatocytes)

168
Q

Spermiogenesis

A

Spermatids -> Spermatozoa (grow tails and discard cytoplasm)

169
Q

Release of sperm into lumen

A

Invaginations in sertoli cells retract releasing sperm

170
Q

Spermatogonium undergoes a mitotic division to produce…

A

Primary spermatocyte

171
Q

Primary spermatocyte undergoes meiosis I to produce…

A

2 secondary spermatocytes

172
Q

2 secondary spermatocytes undergo meiosis II to produce…

A

4 early spermatids

173
Q

What provide nourishment for developing spermatids?

A

Sertoli cells

174
Q

Timing for sperm to be introduced for fertilisation

A

5 day before to 1 day after ovulation
As sperm can last 4-6 days, egg can only survive 1-2 days

175
Q

What carries egg out of ovary

A

Antral fluid
Smooth muscle and fimbriae
Cilia in fallopian tube

176
Q

Capacitation

A

Occurs in female reproductive tract
Maturation of spermatozoon (tails becomes stronger, plasma membrane develops allowing for fusion with egg)

177
Q

Summarise day 1 of fertilisation

A

Fusion of sperm and egg in ampulla

Glycoproteins on zona pellucida are receptors (ZP3) and sperm head contains binding proteins

Binding = acrosome reaction - enzymes exposed to zona pellucida cause it to be digested

Fusion can now occur with plasma membrane

Sperm head passes into cytosol = fertilisation

Fertilisation causes a reaction which changes the cell membrane potential preventing entry of other sperm

This is done by exocytosis of vesicles containing enzymes to inactivate ZP3 hardening zona pellucida

4-7 hours after gamete fusion, meiosis II completes

23 sperm and 23 egg chromosomes migrate to centre cell and the haploid chromosomes fuse

DNA replication occurs

Mitosis begins

178
Q

Sections of fallopian tubes

A

Fimbriae -> Infundibulum -> Ampulla -> Isthmus

179
Q

Summarise days 2-3 of fertilisation

A

Zygote remains in fallopian tube

Oestrogen maintains contractions within tubes

As progesterone increases, smooth muscle relaxes allowing zygote to pass through fallopian tube

Cleavage occurs and each cell is totipotent (can develop into an entire individual)

180
Q

Summarise day 4 of fertilisation

A

Cells flatten
Tight junctions between cells
Polarisation of outer cells
These conditions allow for rapid differentiation

181
Q

Summarise day 5 of fertilisation

A

Fluid filled cavity expands and forms blastocysts
>80 cells
Lost totipotency
Outer cell layer = trophoblast
Then you have inner cell mass and fluid filled cavity in middle

182
Q

Summarise day 5-6 of fertilisation

A

Cavity expands further
Zona pellucida thins

183
Q

Summarise day 6+ of fertilisation

A

Blastocyst expansion
Embryo out of zona pellucida

184
Q

Summarise day 7-9 of fertilisation

A

Late-stage blastocyst hatches and implants in endometrium of uterus

185
Q

Sperm can survive longer in the female reproductive tract with greater glucose availability which comes from..

A

Higher oestrogen levels

186
Q

Placenta composition and development

A

Interlocking foetal and maternal tissues
Outer layer trophoblast (synctiotrophoblast cells invade endometrium)

187
Q

4 placenta roles

A

Nutrition
Gas exchange
Waste removal
Endocrine and immune support

188
Q

What is the chorion?

A

Outermost trophoblast cell layer that supplies embryonic portion of placenta
Extends chorionic villi into endometrium
Release digestive enzymes which break endometrial vessels

189
Q

What forms between the inner cell mass and the chorion?

A

The amniotic cavity - lined by epithelial cells (amniotic sac) which eventually fuses with chorion so there’s only a single combined membrane around foetus

190
Q

Role of fluid in amniotic cavity

A

Buffers mechanical disturbances and temperature changes

191
Q

Human Chorionic Gonadotropin (hCG) production and effects

A

Produced by trophoblasts when they begin endometrial invasion
Maintains of corpus luteum, stimulates oestrogen and progesterone production preventing menstruation

192
Q

Prolactin production and effects

A

Comes from anterior pituitary
Increases end of pregnancy when oestrogen and progesterone decrease
Involved in milk production and prevention of ovulation

193
Q

Relaxin production and effects

A

Increases in early pregnancy
Produced by ovaries and placenta
Limits uterine activity, softens cervix

194
Q

Oxytocin production and effects

A

Comes from posterior pituitary
Secreted throughout pregnancy and increases at end
Stimulates uterine contractions (+ve feedback)

195
Q

Prostaglandins production and effects

A

Initiate labour
Produced by uterine tissue

196
Q

Switch in oestrogen and progesterone production after 3 months of pregnancy

A

Corpus luteum regresses after 3 months
Trophoblast cells of placenta continue to produce oestrogen and progesterone

197
Q

Cardiovascular maternal changes in pregnancy

A

Increased CO
Decreased systemic BP
Decreased total peripheral resistance
Increased uterine blood flow
Increase BV
Increased plasma and blood cell mass

198
Q

Respiratory maternal change in pregnancy

A

Increased alveolar ventilation

199
Q

GI maternal change in pregnancy

A

Increased acid reflux
Delayed gastric emptying - gastroparesis
(Foetus pressing on stomach)

200
Q

Skin maternal change in pregnancy

A

Linea nigra - dark line around central abdomen
Striae gravidae - stretch marks on lower abdomen
Darkened areolar on breasts

201
Q

Biochemical maternal change in pregnancy

A

Weight gain
Increased protein and lipid synthesis
Insulin resistance

202
Q

Cervical ripening

A

Growth and remodelling of cervix
Stimulus oestrogen increases towards end of pregnancy
During pregnancy, uterus sealed by collagen fibres (maintained by progesterone)
Cervix becomes soft and flexible due to collagen breakdown (by oestrogen, progesterone and relaxin)

203
Q

What stimulates oxytocin release pre-labour?

A

Increased prostaglandins

204
Q

What occurs in labour?

A

Increased prostaglandin and oxytocin triggers contraction and pressure in cervix (+ve feedback from the pressure)

Amniotic sac ruptures

Contractions at 10-15 minute intervals moving from top to bottom

As frequency increases, cervix dilates

Stages:
Latent - little dilation (8 hours)
Active - organised contractions (5 hours) - dilation and full expansion
Post-partum - womb contracts and pushes placenta out of vagina

205
Q

Do adrenal and gonad derive from same tissue?

A

Yes

206
Q

Testis present and Leydig cells making testosterone means Wolffian system develops into…

A

Epididymis
Vas Deferens
Seminal Vesicles
Ejaculatory Ducts

Sertoli cells also secrete AMH which leads to Mullerian system regression

207
Q

No testis or Leydig cells = no testosterone = Mullerian system develops into…

A

Fallopian tubes
Uterus
Upper 1/3 of vagina

208
Q

Common gential tubercle at 8 weeks becomes … in male and …. in female

A

Glans
Clitoris

209
Q

3 layers of adrenal gland

A

Zona Glomerulosa - Produces Aldosterone (salt)

Zona Fasciculata - Cortisol (sugar)

Zona Reticularis - DHEA (sex)

210
Q

Negative feedback for cortisol production in the adrenal glands

A

CRH secreted from hypothalamus stimulates ACTH release from hypothalamus which stimulates cortisol production in adrenal glands

Cortisol inhibits release of both CRH and ACTH

211
Q

Sertoli cells secrete AMH resulting in…

A

Mullerian system regression

212
Q

3 phases of growth (infancy-childhood-puberty)

A

Infancy - rapid, decelerates after 2-3 years, determined by nutrition

Childhood - switch from nutritional to hormonal dependence

Puberty - growth spurt, height velocity increase due to GH and sex hormones (14-15 in girls, 16-17 in boys)

213
Q

What is chondrogenesis?

A

growth

214
Q

5 determinants of growth

A

Parental geno/phenotype
Quality/duration pregnancy
Nutrition
Psycho-social environment
Growth promoting hormones

215
Q

Where are GHs synthesised?

A

Somatotroph cells

216
Q

Action of GH

A

Decreases glucose use
Increases lipolysis
Increases muscle mass

217
Q

7 things that stimulate GH production

A

Exercise
Stress
Hypoglycaemia
Fasting
High protein meals
Perinatal development
Puberty

218
Q

5 things that suppress GH production

A

Hypothyroidism
Hyperglycaemia
High carb meals
Glucocorticoid excess
Agings

219
Q

Factors influencing puberty

A

50-80% genetic
Environmental (nutrition)
Leptin production (for appetite)

220
Q

3 types of hormones

A

Steroids
Peptides
Thyroid hormones

221
Q

Role of somatostatin in hypothalamus

A

Inhibits release of GH and TSH

222
Q

2 ways hormones exert their effect

A

Cell surface receptors
Intracellular receptors

223
Q

Time for action in peptides, steroids, thyroid hormones and catecholamines

A

Peptides - min-hour
Steroids - hour-day
Thyroid hormones - day
Catecholamines - sec

224
Q

Thyroid hormones action

A

Basal metabolic rate, growth

225
Q

Parathyroid hormones action

A

Ca2+ regulation

226
Q

Cortisol action

A

Glucose regulation, inflammation

227
Q

6 hormones released by anterior pituitary

A

ACTH, TSH, GH, LH, FSH, Prolactin

228
Q

2 hormones released by posterior pituitary

A

ADH (vasopressin)
Oxytocin

229
Q

Pituitary releases hormones in response to signals from…

A

The hypothalamus

230
Q

Pituitary weight

A

0.5g

231
Q

Anterior pituitary has no arterial blood supply but receives blood through…

A

Portal venous system from hypothalamus

232
Q

What hormone type are TSH, FSH and LH?

A

Glycoprotein

233
Q

What hormone type are ACTH, GH and Prolactin?

A

Polypeptide

234
Q

Releasing hormone (hypothalamus) that stimulates release of TSH from pituitary

A

Thyrotorpin releasing hormone (TRH)

235
Q

Releasing hormone (hypothalamus) that stimulates release of ACTH from pituitary

A

Corticotropin releasing hormone (CRH)

236
Q

Releasing hormone (hypothalamus) that stimulates release of FSH and LH from pituitary

A

Gonadotropin releasing hormone

237
Q

Releasing hormone (hypothalamus) that stimulates release of GH from pituitary

A

GH releasing hormone (GHRH)

238
Q

Releasing hormone (hypothalamus) that inhibits release of GH from pituitary

A

Somatostatin

239
Q

Releasing hormone (hypothalamus) that inhibits release of prolactin from pituitary

A

Dopamine

240
Q

Actions of GH

A

Linear growth in children
Acquisition of bone mass
Stimulates: protein synthesis, lipolysis, glucose metabolism
Regulation of body composition
Psychological well-being

241
Q

Regulation of thyroid hormone levels

A

Hypothalamus releases TRH

Stimulates pituitary to release TSH

Stimulates thyroid to release thyroxine

Thyroxine acts on tissue and has -ve feedback on pituitary and hypothalamus

242
Q

Prolactin inhibition action

A

Inhibits gonadal activity through central suppression of GnRH (thus decreased LH/FSH)

243
Q

Prolactin (PRL) is synthesised by…

A

Lactotrophs

244
Q

Corticosteroid overview

A

Lipid soluble (for passing through membranes)

Binds to specific intracellular receptors

Alter gene transcription directly or indirectly

245
Q

Where are glucocorticoids synthesised?

A

Zona fasciculata and reticularis of adrenal glands

246
Q

Actions of glucocorticoids

A

Increase glucose mobilisation

Maintain circulation (vascular tone, salt/water balance)

Immunomodulation (dampen immune response)

247
Q

Glucocorticoids in circulation

A

90% bound to Corticosteroid-Binding Globulin (CBG)

5% bound to albumin

5% free (only free is bioavailable)

248
Q

Regulation of glucosteroid synthesis by…

A

ACTH

249
Q

What is stress?

A

Sum of bodies response to adverse stimuli (infection, trauma, exercise, etc.)

250
Q

Mineralocorticoids synthesised in…

A

Zona golmerulosa

251
Q

Actions of mineralocorticoids

A

Effects of pancreas, sweat glands, salivary glands and colon

Sodium resorption, decreased sodium content

252
Q

Adrenal androgens

A

Weak androgens generated in adrenal glands

Include oestrogen precursors in postmenopausal women

Production regulated by ACTH

253
Q

Roles of adrenal medulla

A

Synthesises catecholamines

Main site of adrenaline synthesis

254
Q

Relative production of catecholamines in adrenal medulla

A

80% adrenaline, 20% noradrenaline
Dopamine in small amounts

255
Q

Adrenal cortex synthesises… (3)

A

Glucocorticoids
Mineralocorticoids
Androgens

256
Q

Adrenal medulla synthesises…

A

Catecholamines

257
Q

What are pituicytes?

A

Cells of POSTERIOR pituitary gland (cells of anterior named according to the hormone they produce)

258
Q

Pineal gland secretes…

A

melanin

259
Q

What makes a portal circulation?

A

Capillary bed at both ends

260
Q

L and R lobes of thyroid gland unite via..

A

A narrow isthmus

261
Q

Control of thyroid hormone secretion

A

Hypothalamus secretes TRH

Stimulate pituitary to secrete TSH

Stimulates Thyroid to release T3. And also T4 which targets tissue (target tissue releases T3)

T3 and T4 have -ve feedback on hypothalamus and pituitary

262
Q

Process converting T4->T3

A

Deiodination

263
Q

Thyroid hormone action

A

T3 travels through transmembrane transporter (against conc gradient)

Changes mRNA to alter the BMR of the cell

264
Q

Enzyme responsible for production of thyroid hormone

A

Thyroid peroxidase

265
Q

Parathyroid gland role

A

Regulate Ca and phosphate levels
Secrete parathyroid hormone (PTH) in response to: low Ca or high phosphate

266
Q

Actions of PTH

A

Increase Ca reabsorption in renal distal tubule

Increase intestinal Ca absorption

Increase calcium release from bone

Decrease phosphate reabsorption

267
Q

How many parathyroid glands?

A

Superior and inferior at back of thyroid on both lobes (4 total)

268
Q

Normal adult range for PTH

A

1.6-6.9 pmol/L

269
Q

Calcitonin production and action

A

Produced by thyroid c-cells
Inhibits bone resorption (acting directly on osteoblasts)

270
Q

What stimulates bone resorption?

A

PTH (acts directly on osteoblasts)

271
Q

Female HPG axis in FSH and LH release

A

Hypothalamus releases GnRH

Acts on gonadotrophs in anterior pituitary to release LH and FSH

LH stimulates androgen production (oestrogen precursors)

FSH stimulates granulosa cells to converts these oestrogen precursors to oestrogen

272
Q

Male HPG axis in FSH and LH release

A

GnRH release from hypothalamus stimulates gonadotrophs in anterior pituitary to release FSH and LH

LH stimulates Leydig cells to secrete testosterone (-ve feedback of LH and FSH)

FSH stimulates sertoli cells to maintain spermatogenesis (produces inhibin -> -ve feedback of FSH)

273
Q

Growth Hormone release axis

A

Somatostatin from hypothalamus inhibits GH release from anterior pituitary
GHRH from hypothalamus stimulates release of GH from anterior pituitary

GH acts directly to increase blood glucose and bone/tissue growth
GH acts indirectly on liver to produce insulin-like growth factors which contribute to cartilage growth as well as the others in direct pathway

274
Q

3 factors effecting GH release

A

Circadian rhythm
Stress and cortisol
Fasting
(these factors alter GHRH/somatostatin release

275
Q

3 methods of endocrine control of extracellular calcium homeostasis

A

Parathyroid hormone
Vit D
Calcitonin

276
Q

Hypothalamic regulation of GnRH release

A

Kiss neuron releases Kisspeptin neurotransmitter which binds to GPR54 receptor on GnRH neuron triggers release of GnRH

277
Q

HPA axis for cortisol release

A

Stress and Cytokines stimulate CRH release from Hypothalamus
Stimulates ACTH from anterior pituitary
Stimulates Cortisol from adrenal which acts on tissue
(cortisol production has -ve feedback on pituitary and hypothalamus)

278
Q

Relative ‘free’ calcium in the body

A

50% is ‘free’
50% is bound to albumin (so can’t diffuse into cells)

279
Q

Regulation of plasma renin in RAAS

A

Renin produced in kidneys converts angiotensinogen (secreted by liver) to angiotensin I

Angiotensin I -> Angiotensin II by ACE in lungs

Angiotensin II stimulates aldosterone release from adrenal

Aldosterone increases Na reabsorption and K secretion in kidneys

280
Q

What stimulates renin release from kidneys? (3)

A

Decreases renal BP
Prostaglandins
Beta-adrenergic action

281
Q

What suppresses renin release from kidney?

A

ANP
Dopamin

282
Q

What suppresses aldosterone release from adrenal glands?

A

Decreased extracellular [K+]

283
Q

Zonation of adrenal

A

Outer capsule
Cortex (zona glomerulosa -> zona fasciculata -> zona reticularis)
Medulla

284
Q

Where in the adrenal gland does corticosteroid synthesis occur?

A

Cortex

285
Q

What is synthesised in the zona glomerulosa of the adrenal glands?

A

Mineralocorticoids - Aldosterone

286
Q

What is synthesised in the zona fasciculata of the adrenal glands?

A

Glucocorticoids - Cortisol

287
Q

What is synthesised in the zona reticularis of the adrenal glands?

A

Androgens - DHEA

288
Q

What are synthesised in the medulla of the adrenal glands?

A

Catecholamines

289
Q

Uric acid solubility

A

Poorly soluble in plasma
Lower pH, less soluble it becomes

290
Q

Uric acid comes from the breakdown of…

A

Purines (e.g - Adenine, Guanine)

291
Q

3 sources of purines

A

Diet
Breakdown of nucleotides in tissue
Synthesis in body

292
Q

Uric acid removal

A

Excreted in urine
Broken down in gut

293
Q

Dietary purines

A

Meat
Offal
Seafood
Fish
Fructose

294
Q

Allopurinol prevents…

A

Conversion of purines to uric acid

295
Q

Why does alcohol consumption increase uric acid levels?

A

Contains purines

Medicine (14 decks)

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